get/have a cob on

Definition

Slang

  • verb to become angry, display irritation. The term has been used in the Channel 4 TV soap opera Brookside. eric Partridge dated the phrase to the 1930s: the ‘cob’ in question is probably originally a dialect term for a lump or a protrusion, and can be dated back to English slang of the later 18th century.
http://www.dictionarycentral.com/definition/get-have-a-cob-on.html